This change will use the image engine to draw the backdrop of the compositor. With this patch the alpha blending will be done in Linear Scene Reference space and shows pure emissive colors.
See differential for an example image.
**Technical changes**
As only the backdrop drawing is done using the draw manager there are some technical changes.
1. The overlay buffer is partly drawn outside the draw manager. When drawing the backdrop image the overlay buffer needs to be masked to simulate premultiplied alpha under.
2. The backdrop of the node editor is done in region pixel space. A `DRWView` is constructed with this space.
3. UDIM textures uses world position to generate the UV coordinates. This has been implemented more strict by the `IMAGE_DRAW_FLAG_USE_WORLD_POS`. When the flag isn't used the local coordinates are used to generate the UV coordinates what is image space.
4. The draw manager now checks the actual `eSpaceType` of the space data to use different code paths. In the future the movie clip editor will be added.
NOTE: The preview images in nodes are drawn in display space and cannot show pure emissive colors. As preview images are used on more locations it is best to fix this in a separate patch.
Reviewed By: Clément Foucault
Differential Revision: https://developer.blender.org/D9451
When repeat image was active the image was drawn in the foreground
making most uv overlays not visible. This change creates a shared
defined value for repeating and not repeating images.
There are some areas that don't handle pure emissive colors well. For
example erasing alpha using 2d or 3d painting. Or blurring an image in
the compositor.
This patch makes the rendering of pure emissive colors optional. In the
side panel of the Image editor it can still be enabled when needed.
There currently isn't a better place to store it as it is related on how
the image (or a layer of the image) is created. A future design needs to
make sure that the full workflow is supported.
Tiled texture uses different texture structure than normal textures.
Normally we add dummy textures and use them, but I found it cleaner to
have 2 shaders and use the correct shader.
This project moves the current UV/Image editor drawing to the draw manager.
Why would we do this:
**Performance**:
Current implementation would draw each texel per time. Multiple texels could be
drawn per pixel what would overwrite the previous result. You can notice this
when working with large textures. Repeat image drawing made this visible by
drawing for a small period of time and stop drawing the rest. Now the rendering
is fast and all repeated images are drawn.
**Alpha drawing**:
Current implementation would draw directly in display space. Giving incorrect
results when displaying alpha transparent images.
This addresses {T52680}, {T74709}, {T79518}
The image editor now can show emission only colors. See {D8234} for
examples.
**Current Limitations**
Using images that are larger than supported by your GPU are resized (eg larger
than 16000x16000 are resized to 8k). This leaves some blurring artifacts. It is
a low priority to add support back of displaying individual pixels of huge
images. There is a design task {T80113} with more detail.
**Implementation overview**
Introduced an Image Engine in the draw module. this engine is responsible for
drawing the texture in the main area of the UV/Image editor. The overlay engine
has a edit_uv overlay which is responsible to draw the UV's, shadows and
overlays specifically for the UV Image editor. The background + checker pattern
is drawn by the overlay_background.
The patch will allow us to share overlays between the 3d viewport and UV/Image
editor more easily. In most cases we just need to switch the `pos` with the `u`
attribute in the vertex shader.
The project can be activated in the user preferences as experimental features.
In a later commit this will be reversed.
Reviewed By: Clément Foucault
Differential Revision: https://developer.blender.org/D8234
